Can the Carb Heat Ports on a Manifold be blocked without removing the intake?

[AColbe01]

Old girls runs like crap after sitting in traffic or other extended idle situation, rpm drops, runs rough, temp above 210. Gut feeling gas is boiling in the carb, have the phenolic spacer installed but want to keep the heat from ever getting to it. Yea I know the stainless heat shield/ baffel would work better under the carb rather than in the glovebox! Which leads me to wonder how to keep heat from ever gettomg there.

Fuel line is rubber and not touching the manifold!



See how the paint is history.




Here's the intake without the carb.

or

Know I'll make a mess with the coolant and getting the dizzy back where it's supposed to be. I'm better at twisting the key than twisting a ratchet!

Have learned a great deal on this old car though, oddly the song popped in my head as typing, "We'll get by with a little help from our friends!!"

TIA

Andy

 

[mrvette]

IMO, anyone south of Minnesota really doesn't need that heat riser crossover in the manifold.....I have had good success blocking open or removing the heat riser crossover valve off the exhaust mani there, and then removing the intake and filling that crossover passage with Plaster of Paris.....

over the years I have found i'ts the simplest cure for carb heat...must drop the temps by about 2-3000 degrees....

do need to keep the choke active though, obviously.....

here in Florida I somehow don't think any additional carb heat is helpful

In Maryland I found the chokes open just fine after a mile or so of driving in winters as lo as 20 f....

:shocking:

 

[TimAT]

You could plug the 2 holes in the manifold. Best bet would be to pull the intake and block it at the heads.

Look at making that rubber line and plastic filter go away too.

 

[AColbe01]

Rubber Hoses

Want to get the original carb back on the engine, still have the metal lines. Would rather see the original air filter asm back and that too could also bring in a little cooler air to the carb.


Either I can't find the butterfly valve or someone replaced the riser valve with a spacer, didn't crawl under the car. Will add to my todo list.

Plaster of Paris? Non conductive of heat. Easily put in and can be chipped out if needed. Hmmmmmmmmmm


Stopped by PEP boys yesterday to check on intake gaskets but the only one they had with the port blocked was a multi layer aluminum marked reusable, was looking for a set from Felpro for the FI engine.

If you only wanted to do this job once what would you do?

Andy

 

[TimAT]

Steal an aluminum cookie sheet from the wife, cut 2 pieces out of it that were 1/4" bigger than the holes in the heads, stick them on with some RTV and install new gaskets.


Be sure and ask her which cookie sheet she wants to get rid of. Otherwise, do so at your own risk.:suicide:

 

[mrvette]

Tim, I tried various metals and even steel blocking plates in some gaskets did not last for me, I suspect aluminum would melt in a nano second....just like old Pontiac SS headers from '62 or so.....

I remember getting pissed about that long time ago, and a buddy laughed and said Plaster of Paris....

:lol::friends:

 

[TimAT]

Remember when anti-freeze came in metal cans? I've cut up more than one of those for blockoff plates. As long as there's no leak around it the cast iron will carry enough heat away. And a cookie sheet is kind of designed for hi-temp. IF you're real concerned, get a stainless pancake turner.

 

[AColbe01]

Plaster of Paris or "I'm in the dog house" cut up pancake flipper, intake still has to come off engine!

 

[mrvette]

Plaster of Paris or "I'm in the dog house" cut up pancake flipper, intake still has to come off engine!

Dawg house?? Linda and I just bought a very old camper, she wants to keep the cats in cages on the cab over sleeper......

that's ain't going to work....:stirpot::noworry:

 

[SmokinBBC]

Just wondering........what carb are you running? Are you going to put your qjet back on?

 

[big2bird]

I know Darrow blocked his off. SS I believe.
The last one I did was aluminum, and I just had it welded closed. Easy enough to drill out ata later time, but does you no good I know.

 

[AColbe01]

Just wondering........what carb are you running? Are you going to put your qjet back on?

Carter AFB, shaft holes egged out and gas tended to pool on top of the intake!


Had the carb rebuilt and the guy put it on his test engine, said no problem with the fuel leaking, wondered about my engine and vacuum created.

Thanks,

Andy

 

[SmokinBBC]

Just wondering........what carb are you running? Are you going to put your qjet back on?

Carter AFB, shaft holes egged out and gas tended to pool on top of the intake!


Had the carb rebuilt and the guy put it on his test engine, said no problem with the fuel leaking, wondered about my engine and vacuum created.



Thanks,

Andy

My '70 qjet has a hot idle compensator on it. It has a bimetal strip and valve which allows additional air into the carb which solves the problem of enriched Air Fuel ratio on a hot engine due to extended idle time, etc. I don't know which carbs had it though.

Here's a link.

http://www.tpub.com/content/construction/14264/css/14264_138.htm

 

[lars]

Just wondering........what carb are you running? Are you going to put your qjet back on?

That year Vette didn't use a Q-Jet - it used the Rochester 4-Jet or a Carter AFB.

You can plug the exhaust crossover under the carb using a pipe plug at either end of the crossover slot - run a pipe tap into the holes and then run the plugs in. It will effectively block the heat passage. If you don't do this, you have to make sure you're running the correct "gasket pack" to prevent the carb from getting too hot: The gasket pack consists of a high-temp gasket on the manifold following by a stainless steel shield. If you do not use this stock gasket setup, you will boil the fuel in the carb.

The rubber line is bad for putting heat into the fuel - get rid of the rubber line and use a steel line.

Lars

 

[AColbe01]

Just wondering........what carb are you running? Are you going to put your qjet back on?

That year Vette didn't use a Q-Jet - it used the Rochester 4-Jet, which is not a Q-Jet.

You can plug the exhaust crossover under the carb using a pipe plug at either end of the crossover slot - run a pipe tap into the holes and then run the plugs in. It will effectively block the heat passage. If you don't do this, you have to make sure you're running the correct "gasket pack" to prevent the carb from getting too hot: The gasket pack consists of a high-temp gasket on the manifold following by a stainless steel shield. If you do not use this stock gasket setup, you will boil the fuel in the carb.

The rubber line is bad for putting heat into the fuel - get rid of the rubber line and use a steel line.

Lars

Yes Sir!!!!